scholarly journals Study of the Intrinsic Fluorescence of a Highly Branched Cationic Dendrimer, Poly(Ethyleneimine) (PEI)

Molecules ◽  
2019 ◽  
Vol 24 (20) ◽  
pp. 3690
Author(s):  
Viktória Tóth ◽  
Péter Hermann ◽  
Dániel Végh ◽  
Tivadar Zelles ◽  
Zoltán Géczi
Keyword(s):  
Solar Cell ◽  
Fluorescence Intensity ◽  
Mass Concentration ◽  
Reliable Method ◽  
Direct Method ◽  
Molar Concentration ◽  
Amino Groups ◽  
Molecular Weights ◽  
Ph Values ◽  
Tertiary Amino

Poly(ethyleneimine) (PEI) is a weakly basic, synthetic, polycationic polymer, due to the presence of primary, secondary, and tertiary amino groups. The amino groups are responsible for the variety of applications of PEI (e.g., transfection, bioimaging, solar cell, etc.). Our study presents some new and reproducible methods for the quantification of molecular or mass concentration of highly branched PEI of different molecular weights (800–2000–25,000–750,000 MW PEI). In the course of the direct method, spectrophotometry and fluorometry were applied to determine the absorption and fluorescence of PEI dilution series. An increase in the MW at the same concentration produces a higher count number because of the higher number of amino groups in PEI molecules. The character of increment in fluorescence intensity is essentially different in the case of mass concentrations and molar concentrations. The increment of the fluorescence intensity related to the molar concentration is non-linear. In the case of mass concentration, the slope is linear. Moreover, their fluorescence is enhanced with the decrease in pH values. The spectrophotometry is a reliable method for measuring the quantity of PEI molecules in solution. Our data help in recognizing the detailed properties of PEI in dendrimer research.

scholarly journals Spectrofluorimetric Determination of Some N. Containing Medicines Using Rhodamine 6G as a Chromogenic Reagent

2021 ◽  
Vol 22 (2) ◽  
pp. 367-375
Author(s):  
Theia'a Najim Al-Sabha ◽  
Mohamed Yahya Dhamra
Keyword(s):  
Fluorescence Intensity ◽  
Rhodamine 6G ◽  
Pharmaceutical Preparations ◽  
Detection Limits ◽  
Ion Pair ◽  
Amino Groups ◽  
Spectrofluorimetric Method ◽  
Spectrofluorimetric Determination ◽  
Tertiary Amino

A sensitive spectrofluorimetric method has been developed for the analysis of some medicines containing primary, secondary, and tertiary amino groups, namely Diclofenac (DIC), Domperidone (DOM), Famotidine (FAM), and Propranolol (PRO), in their pure and medicinal forms. The method is based on the quenching of the fluorescence intensity of rhodamine 6G (R6G) through the formation of ion-pair complexes between the above medicines and the R-6G reagent, which is measured at 552 nm after excitation at 402 nm. The calibration graphs were rectilinear in the concentration ranges of 0.10- 9.00, 0.05-15.00, 0.10-14.0 and 0.05-5.00 µg mL-1 for above medicines respectively. The recovery (%) values were ranged between 99.45%- 100.97%. The detection limits ranged in the concentration of 0.243-0.754 µg/mL, and the limits of quantitation were 0.806- 2.420 µgmL-1 for all drugs. The method was successfully applied for the determination of these drugs in their pharmaceutical preparations.

Biphenyl-Derivatives Possessing Tertiary Amino Groups as β-Secretase (BACE1) Inhibitors

2010 ◽  
Vol 7 (7) ◽  
pp. 507-515
Author(s):  
Simone Bertini ◽  
Elisa Ghilardi ◽  
Valentina Asso ◽  
Carlotta Granchi ◽  
Filippo Minutolo ◽  
...  
Keyword(s):  
Amino Groups ◽  
Tertiary Amino

Synthesis and Luminescence Properties of Tb3+-Doped Hydroxyapatites

2011 ◽  
Vol 399-401 ◽  
pp. 1582-1587
Author(s):  
Su Ping Huang ◽  
Jun Zhu ◽  
Ke Chao Zhou
Keyword(s):  
Aspect Ratio ◽  
Fluorescence Intensity ◽  
Doping Concentration ◽  
Doping Content ◽  
Fluorescent Properties ◽  
Strong Fluorescence ◽  
Active Growth ◽  
Ph Values ◽  
Structure Morphology ◽  
Ultraviolet Ray

In this paper, the terbium -doped nano-HA powders with strong fluorescence was prepared by hydrothermal synthesis and its crystal structure，morphology and fluorescent properties are characterized by XRD, TEM, XPS, ICP and PL spectroscopy. Results showed that with the doping concentration of Tb3+increasing, the aspect ratio of Tb3+-doped HA particles decreased, while the fluorescence intensity excited by ultraviolet ray at 272 nm is significantly enhanced. With pH values increased from 6.5 to 10.0, the aspect ratio of Tb3+-doped HA decreased greatly, and the morphology of nano-Tb:HA particles changes from rod particles to equiaxed particles and the actual doping content and the fluorescence intensity tends to increase correspondingly, which can be explained that under alkaline solution, Tb3+was more easier entering the HA crystal, and the Tb3+would substitute the Ca2+ in both hydroxyapatite Ca(Ⅰ) and Ca(Ⅱ) site, which may block the active growth sites of the seed crystals and resulted in the growth rate and the ratio of length to radius decreasing.

NEW ANION-EXCHANGE RESIN BASED ON CROSS-LINKED SAWDUST CONTAINING TERTIARY AMINO GROUPS GRAFTS

2000 ◽  
Vol 39 (4) ◽  
pp. 723-733 ◽  
Author(s):  
N. A. IBRAHIM ◽  
M. H. ABO-SHOSHA ◽  
E. EL-ALFY ◽  
Z. EL-SAYED
Keyword(s):  
Anion Exchange ◽  
Exchange Resin ◽  
Anion Exchange Resin ◽  
Amino Groups ◽  
Tertiary Amino

scholarly journals Synthesis and Properties of Nitrogen-Doped Carbon Quantum Dots Using Lactic Acid as Carbon Source

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 466
Author(s):  
Kaixin Chang ◽  
Qianjin Zhu ◽  
Liyan Qi ◽  
Mingwei Guo ◽  
Woming Gao ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Lactic Acid ◽  
Fluorescence Quenching ◽  
Functional Groups ◽  
Fluorescence Intensity ◽  
Carbon Quantum Dots ◽  
Nitrogen Doped ◽  
Ph Values ◽  
Wide Range ◽  
Nitrogen Doped Carbon

Nitrogen-doped carbon quantum dots (N-CQDs) were synthesized in a one-step hydrothermal technique utilizing L-lactic acid as that of the source of carbon and ethylenediamine as that of the source of nitrogen, and were characterized using dynamic light scattering, X-ray photoelectron spectroscopy ultraviolet-visible spectrum, Fourier-transformed infrared spectrum, high-resolution transmission electron microscopy, and fluorescence spectrum. The generated N-CQDs have a spherical structure and overall diameters ranging from 1–4 nm, and their surface comprises specific functional groups such as amino, carboxyl, and hydroxyl, resulting in greater water solubility and fluorescence. The quantum yield of N-CQDs (being 46%) is significantly higher than that of the CQDs synthesized from other biomass in literatures. Its fluorescence intensity is dependent on the excitation wavelength, and N-CQDs release blue light at 365 nm under ultraviolet light. The pH values may impact the protonation of N-CQDs surface functional groups and lead to significant fluorescence quenching of N-CQDs. Therefore, the fluorescence intensity of N-CQDs is the highest at pH 7.0, but it decreases with pH as pH values being either more than or less than pH 7.0. The N-CQDs exhibit high sensitivity to Fe3+ ions, for Fe3+ ions would decrease the fluorescence intensity of N-CQDs by 99.6%, and the influence of Fe3+ ions on N-CQDs fluorescence quenching is slightly affected by other metal ions. Moreover, the fluorescence quenching efficiency of Fe3+ ions displays an obvious linear relationship to Fe3+ concentrations in a wide range of concentrations (up to 200 µM) and with a detection limit of 1.89 µM. Therefore, the generated N-CQDs may be utilized as a robust fluorescence sensor for detecting pH and Fe3+ ions.

scholarly journals Characterization of Melanoidins and Color Development in Dulce de Leche, a Confectionary Dairy Product With High Sucrose Content: Evaluation of pH Effect, an Essential Manufacturing Process Parameter

2021 ◽  
Vol 8 ◽  
Author(s):  
Analía Rodríguez ◽  
Patricia Lema ◽  
María Inés Bessio ◽  
Guillermo Moyna ◽  
Cristina Olivaro ◽  
...  
Keyword(s):  
Enzymatic Hydrolysis ◽  
Ph Effect ◽  
Dairy Product ◽  
Gel Filtration ◽  
Significant Degree ◽  
Product Analysis ◽  
Molecular Weights ◽  
Ph Values ◽  
Initial Ph

The effect on color of the initial pH employed in dulce de leche (DL) production was evaluated through physicochemical and spectroscopical characterization of the melanoidins formed in the process. Melanoidins originated at pH values of 6.5, 7.0, and 7.5, and they were released by the enzymatic hydrolysis of the protein backbone and purified by gel filtration. They showed a significant degree of polydispersity, in general, with molecular weights (MWs) below 1,800 Da. DL produced at a higher pH released melanoidins with higher average MW after the enzymatic hydrolysis. They also presented darker colors (dE*ab, C*), more closely resembling those typical of the commercial product. Analysis of the fractions isolated by gel filtration using HPLC-DAD and multinuclear NMR showed an heterogeneous and complex composition. Even though structurally related, the 1H NMR spectra of melanoidins showed a higher degree of aromaticity at higher pH values. In conclusion, the pH employed in DL production affects the amount and structure of the colored products originated by MR reactions, and thus the color of the final product.

Polyacrolein microspheres as a new tool in cell biology

1982 ◽  
Vol 56 (1) ◽  
pp. 157-175
Author(s):  
S. Margel ◽  
U. Beitler ◽  
M. Ofarim
Keyword(s):  
Cell Biology ◽  
Polymerization Process ◽  
Amino Groups ◽  
Ph Values ◽  
Human Red Blood Cells ◽  
Primary Amino ◽  
Aldehyde Groups ◽  
Potential Use ◽  
Specific Labelling ◽  
Reactive Aldehyde

Polyacrolein (PA) microspheres in sizes ranging from 0.04 micron to 40 microns were synthesized. Magnetic and fluorescent PA microspheres were formed by carrying out the polymerization process in the presence of appropriate ferrofluidic or fluorochromic compounds, respectively. The microspheres carry reactive aldehyde groups, through which various ligands, containing primary amino groups, were covalently bound at physiological pH values. The potential use of these microspheres was demonstrated by the specific labelling of fresh human red blood cells (RBC) and by the separation of human RBC from turkey RBC by means of a magnetic field. PA microspheres were also bound covalently to the anti-allergic drug disodium chromoglycate (DSCG) and the conjugate was used for the labelling of rat basophilic leukaemia cells.

scholarly journals Biodegradation of low molecular weight polyacrylamide under aerobic and anaerobic conditions: effect of the molecular weight

2020 ◽  
Vol 81 (2) ◽  
pp. 301-308 ◽  
Author(s):  
Wenzhe Song ◽  
Yu Zhang ◽  
Amir Hossein Hamidian ◽  
Min Yang
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Carbon Chain ◽  
Anaerobic Treatment ◽  
Low Molecular Weight ◽  
Amino Groups ◽  
Molecular Weights ◽  
Weight One ◽  
Hydrolysis Of ◽  
Aerobic And Anaerobic

Abstract The biodegradation of polyacrylamide (PAM) includes the hydrolysis of amino groups and cleavage of the carbon chain; however, the effect of molecular weight on the biodegradation needs further investigations. In this study, biodegradation of low molecular weight PAM (1.6 × 106 Da) was evaluated in two aerobic (25 °C and 40 °C) and two anaerobic (35 °C and 55 °C) reactors over 100 days. The removal of the low molecular weight PAM (52.0–52.6%) through the hydrolysis of amino groups by anaerobic treatment (35 °C and 55 °C) was much higher than that of the high molecular weight (2.2 × 107 Da, 11.2–17.0%) observed under the same conditions. The molecular weight was reduced from 1.6 × 106 to 6.45–7.42 × 105 Da for the low molecular weight PAM, while the high molecular weight PAM declined from 2.2 × 107 to 3.76–5.87 × 106 Da. The results showed that the amino hydrolysis of low molecular weight PAM is easier than that of the high molecular weight one, while the cleavage of its carbon chain is still difficult. The molecular weights of PAM in the effluents from the two aerobic reactors (25 °C and 40 °C) were further reduced to 4.31 × 105 and 5.68 × 105 Da by the biofilm treatment, respectively. The results would be useful for the management of wastewater containing PAM.

scholarly journals The compressibility of aqueous solutions II

1934 ◽  
Vol 146 (858) ◽  
pp. 640-650 ◽  
Keyword(s):  
Pressure Range ◽  
Direct Method ◽  
Direct Methods ◽  
Cane Sugar ◽  
Excess Pressure ◽  
Subsequent Work ◽  
Molecular Weights ◽  
In Series ◽  
Related Compounds ◽  
A Direct Method

In an earlier communication, Perman and Urry described the measurement, by a direct method, of the compressibility coefficients of aqueous solution of urea, cane sugar, potassium chloride, and calcium chloride, over a range temperatures and concentrations. Their work was over the pressure range 0-200 atmospheres excess pressure. They were able to apply their together with other data obtained by their co-workers, to an extension Porter's theory of compressible solutions, and thus obtained values for osmotic pressures of those solutions which agreed very well with the obtained by more direct methods. The present work is a continuation of this and subsequent work (unpublished) by these authors. It was intended, especially, to investigate the effect of nature of the solute molecule upon the compressibility, and, for this reason the choice of solutes was particularly important. A number of series chemically related compounds were used where only one part of the mole varied in a progressive manner from substance to substance. In series there was no chemical relationship, but the members had the empirical formula and their molecular weights were therefore simple multi of each other.

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